1. Field of the Invention
This invention relates to a compressed sheet to be used as a gasket base material, for example, in a motorcar, a ship, various kinds of apparatuses or the like.
2. Description of the Prior Art
As this kind of compressed sheet, those of asbestos make have been conventionally used. However, out of consideration of hazards to the human body or the like, many kinds of alternative products have been proposed. For example, as disclosed in the Japanese Published Unexamined Patent Application No. 129377/1987, there is known a compressed sheet comprising: base fibers constituted by inorganic fibers other than asbestos, organic fibers or a combination of both; a rubber; rubber chemicals; and fillers. This kind of compressed sheet is manufactured by forming a compressed sheet which comprises: base fibers constituted by inorganic fibers other than asbestos, organic fibers, or a combination of both; a rubber; rubber chemicals; and fillers is processed by feeding it between a pair of rolls comprising a hot roll and a cold roll, thereby laminating the composition into a sheet-shaped material on the hot roll. The sheet-shaped material is then peeled off the roll.
However, the asbestos-replaced compressed sheet (i.e., asbestos is replaced by another material to make it asbestos-free) as proposed in the aforementioned patent application has a larger creep relaxation than the compressed sheet of asbestos make, resulting in a possibility of inducing a phenomenon of torque loss. Therefore, a proposal for an asbestos-replaced compressed sheet having an improved creep relaxation has been awaited.
In addition, the method of manufacturing the asbestos-replaced compressed sheet as proposed above has a problem in that the composition forming the compressed sheet is likely to be adhered to the cold roll at an end period of feeding during processing, resulting in a poor workability and variation in properties in the compressed sheet obtained. Consequently, it is rather time-consuming to pick up only the joint sheets of acceptable quality by throwing away those of unacceptable quality.
Accordingly, it is an object of this invention to provide an asbestos-replaced compressed sheet which satisfies the aforementioned requirements, and a method of manufacturing an asbestos-replaced compressed sheet which solves the aforementioned problems.